Dresser attachment for grinding machines



Sept l, 1942-' J. c. wlLsoN 2,294,492

DRESSER ATTACHMENT FOR GRINDING MACHINES Filed Aug. 28, 1940 4SheetsfSheet l Fl G. i

e y L ATTORNEYS Sept. l, 1942. J; c. wlLsoN 2,294,492'

DRESSER ATTACHMENT FOR GRINDING MACHINES Filed Aug. 28, 1940 4Sheets-Sheet 2 v g -ArroR//fys Sept. 1, 1942. .1. c. WILSON 2,294,492

DRESSER ATTACHMENT FOR GRINDING MACHINES Filed Aug. 28, 1940 4Sheets-Sheet I Sept l, 1942- .Y J. c. wlLsoN 2,294,492

DRESSER ATTACHMENT FOR GRINDING MACHINES Filed Aug. 28, 1940 4Sheets-Shea?,` 4

.By a SMM. .mhd/ww ATTO/mm ery of the wheel first in one direction, thenPatented Sept. l, 1942 DRESSEB ATTANT MAC John C. wilson, The ThompsonFOB GRINDING EINES` a corporation of Ohio Application August 28, 1940,Serial No./354,555 21 claims. (ci. 125-11) The present invention relatesto grinding machines, and more particularly to a dresser attachment forthe machine.

In the fabrication of machine chine elementsy particularly for aircraftengine tools and maand similar production, it is often necessary to Aprovide a grinding Wheel which has an abrading surface of irregularconfiguration; The arrangement is such that the grinding wheel leavesthe impression of its irregular surface on the tools orelements beingground. ,This impression may be obtained from a wheel having an outerperiphery of uniform diameter and terminating at each edge of the wheelin a rounded surface. The radii of these rounded surfaces, as well asthe uniformity of the straight peripheral portion, must be accuratelydetermined and maintained during the grinding operation.

In the case of quantity lproduction, for ex- I ample when simultaneouslygrinding a group of aircraft engine rods by passingthe wheel first inone direction and then in the opposite direction over the rods, and thengrinding a successive group of rods in the same manner, it becomesnecessary to always maintain the grinding wheel in a dressed condition.The dressing operation must be such that the wheel will have the same yperipheral shape, after being dressed, that it had before the dressingoperation if the successive groups of engine rods are to conformstrictlyto /the predetermined dimensions and shape. Heretofore wheels wereusually dressed by a hand tool provided with a diamond nib, particularlythose Wheels of complicated shape as when the edges were rounded-over sothat the accuracy with which the dressing operation was performed woulddepend solely on the experience and skill of the dressing operator.

The primary object of the present invention is to provide an improvedwheel dressing attachment for a grinding machine, and in which thedressing tool is caused faithfully to follow not only the irregularitiesof the wheel periphery but also the rounded edges at each side of theWheel.

Another object is to provide an attachment, as explained above, in whichthe dressing tool is caused to move over the periphery of the wheel in apredetermined path, including a circular path' at each edge of thewheel.

The iinal object is to provide a dresser tool mechanism in which thetool is caused to pass and accurately follow the entire grindingperiphspringfield, ohio, assigner to Grinder Co., Springfield, Ohio,

the opposite direction and over the rounded surfaces formed at each edgeof the wheel.

The above objects are attained, in brief, by securing the dresser toolto a crank which is attached to a shaft, the latter being caused torotate through a given arc by which the tool is drawn over one of therounded surfaces, vthen the shaft is moved in a plane parallel to themain periphery of the grinding Wheel during which time the tool is movedover such periphery. The

' shaft is then rotated in a direction opposite its original rotationtocause the tool to describe an arc corresponding to the rounded edge atthe opposite side of the wheel, and on conclusion o f the entiremovement the tool is caused to retrace its path so that the grindingwheel is dressed twice and over its entire cutting surface, includingboth roundededges.

All of the various movements of the dresser tool are made frictionlessby the use of ball bearings, vand ample adjustment is provided throughWedge-shaped gibs in order to take up the wear.

The invention will be better understood'when the following specificationis perused in connection with the accompanying drawings.

In the drawings:

Figure 1 is a side elevational view of the upper portion of a typicalform of grinding machine which is provided with the improveddresserfattachment. Certain machine elements, such as aircraft enginerods, which lend themselves to quantity production and fabrication, areshown in position ready to be ground by a wheel that has previously beendressed by the, improved attachment.

Figure 2, is a side elevational view of the improved dresser attachment.

'Figure 3 is also an elevational view looking toward the left-hand endof the structure shown in Figure 2.

Figure 4 is a cross sectional view taken along the line 4-,4 in Figure2. i

Figure 5 is a sectional view taken along line 5-5 in Figure 3 throughthe length of the attachment, down the middle, but showing certainparts, including the shaft and crank, in elevation.

Figure 6 is a fragmentary elevational view looking at the lowerright-hand end of the structure shown in Figure 5, but with the pilotvalve broken away in section to show its internal construction.

Figure 7 is a fragmentary perspective view showing the structuralrelationship between the rack, pinion, crank' shaft and shoe by whichthe in crank which carries the diamond nib is caused except the lowerabrading surface. is secured to the frame 9 of the machine. The

to describe a path corresponding to the'perihery of the grinding wheel.

Figure 8`is a perspective. view of a template which cooperates with theshoe shown in Figure 'l in order to obtain the predetermined movement ofthe crank and its shaft.

Figure 9 is a diagrammatic view showing the dresser tool at thebeginning of its dressing operation, and also depicting the relativepositions of the control mechanism by which the tool is caused to moveover theperiphery of the grinding wheel. In this view (as well as inFigures 10 and 11) the grinding wheel has been shown above its truepositionv for the sake of clarity,

Figure 9.

In general, the attachment is of a character that it may be bolted inplace to the reciprocating work table of a grinding machine, and sopositioned that at any desired time the table may be moved with respectto the grinding wheel and the attachment operated to cause the diamondnib to dress the periphery of the wheel. The work table of the grindingmachine is designated in Figure 1 by the reference character I. Theapparatus to be described, with the exception of the source of pressureuid, iscarried on a base 2 (Figure 5) which may be bolted to the tableI.

As shown in Figure 1, the attachment comprises a crank generallydesignated 3 and carrying a diamond nib'l, the crank being connected toa mechanism contained within a box 5 which gives the crank three typesof motion. a rotating motion around one edge of the grinding wheel,

a lateral motion over the straight periphery ofthe grinding Wheel, andfinally a rotary motion the crank and its mechanism are caused byahydraulic cylinder, also contained within the box 5, the piston withinthe cylinder being controlled by a pilot valve contained within the boxI. The

grinding wheel is indicated in Figure 1 by the reference numeral 1, andthere is the usual steel guard 8 inclosing practically all of the wheelThe guard hand wheel Il controls the lateral movement of the grindingwheel on its dovetail slide I as is well known in the art.

The work being ground 'has been typically illustrated by a group ofaircraft engine rods I2 which are clamped in position between twoupstandlng work holders I3, supported on a base I4 which is bolted as atI5 to the table of the machine. These engine rods have a congurationthat requires rounded surfaces at each end, separated by a ilat surface.'I'he distance be- 'tween theserounded surfaces or fillets might be thesame as thethickness of the grinding wheel I or may be greater than thisthickness so that in order to grind both of the rounded surfaces in atransverse direction, asis well known in the art. It is"apparent thatunder these conditions the ounded edges. ofthe wheel must conform stricly to a predetermined radius, and this dimensionmust be rigidlymaintained during the successive grinding of each group of the venginerods in order that the latter might have strictly the same finisheddimensions. When the-grinding wheel requires dressing it is desirablethat the dressing tool be brought-under the wheel in vsuch a positionthat the diamond nib'4 is caused to dress the periphery ofthe wheelincluding the rounded edges, and this dressing operation must beaccurately performed from time to time depending on the dressingrequirements. The structural details ofthe improved dressing attachmentare illustrated for the most part in Figures 2, 3, 4 and 5.

'I'he diamond nib 4 is secured in any suitable manner to a hub I6 whichis carried on the end of the crank 3, the latter being typified as aflat memb'er provided with reeiforcing webs II (Figure 5). The left-handend of the crank 3 (Figure 5) terminates infa round shoulder`mem ber I8which is carried on a crank shaft I9. The latter is contained within abarrel casting 2i), which has a general circular configuration asindicated in Figure 4, and is provided at each side with an arch-shapedwing' 2|. The purpose for this wing-shaped extension will be explainedhereinafter. The barrel casting 20 is provided ateach end with a rollerbearing 22 which serves as a rotatable support for the shaft I9. To theend of the barrel casting 2li opposite the shoulder member I8 there issecured a cap 23, hollowed out to receive a nut' 2l which engagesthreads 25 cut on the shaft. The purpose of this nut is v simply toy/maintain the axial position of the shaft. y.

Intermediate the ends of the shaft vand also contained within the barrelcasting 20 there is av hubbed pinion 28, keyed to the shaft as indicatedat 21, this pinion being adapted to mesh with the teeth 28 of a rack 29(Figure 7). The rack 29 is supported on and secured to a dovetail slide30 by means of screws 3l, this slide being adapted to move in acorresponding groove formed at the upper surface of a solid block ofmetal 32 which forms an integral part of the base 2 (Figure 5). In orderto take up wear between the dove-tail slide member 30 and the sides ofthe groove there may be provided a tapered gib 33 longitudinallyadjustable by a screw 3Q, as is well known inthe art. The adjustmentshould be such as freely to permit relative longitudinal movementbetween the slide 30 and ,theialock 32 under conditions which will beexplained hereinafter.

The blok32 is provided at each side of its upper surface with a cutawayportion to receive a rail 35. Each rail is provided with a V-shapedgroove at its outer surface, these grooves being adapted to receive ballbearings 36 spaced apart itis necessary automatically to move the tableI ment between thebarrel casting 20 and the Vmetal block 32, carryingwith it the shaft I9, the pinion 26, rack 29 and the dove-tail slide30,.

' The shaft I9 carries at its end beyond the cap 23 a shoe, generallydesignated 4I, and having a cylindrical portion 42 positioned onopposite sides` of a triangular portion 43. The shoe is keyed to theshaft, as indicated at B4. The flat portion of the shoe 4I rests on atemplate 46 (Figure 5), the details of which are shown in Figure 8. Thetemplate is constituted of two at plates 41 spaced from one another by apair of fiat intermediate blocks 48, and all doweled i together asindicated at 49, and screwed as indicated at 50. The plates 61 areprovided at their upper edges with a pairof spaced circular notches 5I,the notch of one plate being in line with the corresponding notch of theother plate to form the general arrangement shown in Figure 8. Thecenters of curvature of these notches liein the horizontal planecontaining the center line of the crankshaft I9. The spacing of thenotches is determined by the width of the straight portion of thegrinding wheel periphery, as will be explained hereinafter. The template55 is held in place by a grooved block 5i" which rests in a groove on abracket 52 having supporting ribs 53. The bracket has an L-shaped formand is screwed to the block 32 as indicated at 55.

vIn order to regulate the,vertical position of the shoe 5i, thuspreventing strain on the shaft I9, there may be provided a tapered gib55 positioned between the lower surface of the block 5i andthehorizontal surface of the groove in the member 52. The position of thetapered gib 55 may be adjusted by a screw 55'v (Figure 2).

cooperating contact elements will be pointed out hereinafter.

For controlling the piston 51 in the hydraulic cylinder there isprovided a two-way pilot valve, generally designated 68 and illustratedin Figure 6. This valve may be formed of la cylinder contained withinthe block 32, and has a cooperating valve rod 69. This rod is providedwith three enlarged portions 1li, 1| and 152, so spaced with respect tothe pressure fluid inlet and outlet conduits as to control pressurefluid which is admitted to the opposite sides of the piston 51 insuccession. Conduits are taken from a source of pressure fluid, whichmay be an oil pump (not shown), these conduits entering the pilot valveas indicated by the dotted circle 13 which represents the inlet, and thecircle 14 which represents the outlet from the valve. A conduit 15istaken from the pilot valve to the right-hand side of the piston 51(Figure 4), and a conduit 16 connects the left-hand side of the pisto tothe valve. common exhaust passageway 1 is taken from three positionsalong the cylinder of the valve,

The block 32 is hollowed out to form a cylinder 55. Within this cylinderthere is a hydraulic piston 51 secured to a shaft 58 which extendsthrough a combined packing box and retaining plate 59 of any suitableconstruction, the latter being secured to the cylinder by means ofscrews 5@ (Figure 4). A cap 5l may be screwed over the combined packingand retaining elementj. The left-hand end of the shaft (Figure 4) 'issecured to a downwardly extending lug or bracket 62 which is screwed asindicated at 53 to the dove-tail slide 35. The arrangement is such thatas the piston 51 is caused to reciprocate within the cylinder 55, underconditions which will be explained presently, the dove-tail slide 3l) isgiven a similar motion with respect to the block 32, causing the rack 29to communicate its longitudinal movement to the pinion 25. During oneportion of the operation the pinion is permitted to rotate, thusrotating the shaft i5,

'but during another portion of the operation the pinion is not permittedto rotate so that the effect of the rack is to cause the barrel casting20, and all of--the contained elements, to be moved transversely of theblock 32. It is apparent that the arch-shaped wings 2i of the barrelcasting have an interior dimension of arch sumcient` to clear the rack29.

Secured to the opposite end faces of the block 32, as seen in Figure 4,there is a pair of upstanding bifurcated bra'ckets 55 at -each end, eachof these brackets carrying an adjustable' stop screw 65 which may betightly secured in any desired position by means of a clamping screw 66which spans the bifurcated portion of the bracket. rContact elements 51are provided on the opposite end surfaces of the wing portions 2l of thebarrel casting in line with the stop screws 65. The purpose of thesescrews and the this passageway communicating with the outlet conduit 1t(Figure 6) The arrangement is such, and assuming that the valveshaft'has the same position as shown in Figure 6, that pressure fluidfrom the pump is admitted to the valve at the conduit 13 and passesthrough the compartment formed by the enlarged portions 1B, 1l, into theconduit 15, and is admitted to the right of the piston 51 (Figure 4).However, as the rod 69 is moved' to the positioned between the conduitinlets 15, 13,pre-

venting pressure fluid from flowing into the con--l .covered thatpassageway. Under these conditions the pressure fluid inlet 13 is now incommunication with the conduit 1S, and the exhaust passageway to thisconduit is closed by the portion 12 so that pressure uid is now admittedto the left-hand side of the piston 51 (Figure 4); and the right-handside of the piston is now open to exhaust. Consequently, by moving thevalve rod 55 either to the left or right pressure uid is caused to entereither one side or the other side of the piston 51.

In order to control the position of the rod 59 there is provided thefollowing mechanism: Projecting outwardly from the side of the block 32there is a 'bracket 18 having an opening which re'- ceives the rod 55. Acollar 19 is pinned to the shaft, and between the collar and the bracket18 there is a compression spring 80. A pin 8l extends outwardly from theblock 32, this pin serving as a pivotfor a latch 82, to which is rigidlysecured a trip lever 83. Directly in line with the trip lever there is.a dog 35, bolted asindicated atl 55 to the shoulder member i8 of theshaft i9, the arrangement being such that as the shaft is rotated thedog will be caused to strike the lever 83.

Complete operation designated position No. l (not shown on the l.

drawings). It will be noted that the axis of thc left (Figure 6), theenlarged portion 1I is nowV l shaft I9 coincides (as indicated by thedotted line) with the center point a: of the rounded v that the dog 84carried'by the shoulder member.`

I8 will also extend upwardly and outwardly as indicated in Figure 9. Inorder to cause the diamond nib 4 to move downwardly around the curvededge and to the left. the knurled knob 88 is pulled to the left, causingthe collar 19 to place the spring 80 under compression so that when theknob is released the collar 19 will contact the left-hand end of thelatch 82, causing the trip lever 83 to be moved to the right. This isthe position indicated in Figure 9.

A similar position has also beenl illustrated in Figure 6 except thatthis view -has been taken from the opposite side of the pilot valve ofFigure 9, so that the knob'86 in Figure 6 would actually be moved to theright. It will be noted that the inlet conduit 13 of the pressure fluidline is in communication with the conduit 15, by which fluid is admittedto the right-hand side of the piston 51 in the main cylinder (Figul'ed).The piston will then move to the left, carrying with it the rack 29.

A left-hand movement of the rack, as seen in Figure 7. will cause aclockwise rotation of the pinion 28, causing the circular hubs 42 of theshoe 4I to be rotated within the right-hand pair of circular notches Iof the template 46. During this time the rotation of the shaft causesthe shoulder member I8 to rotate,carrying with it the crank 3, also thediamond nib which is secure the hub portion I8 of the crank. Since the cnter point :c (Figure 9) of the curve b,

.the axis of the shaft I9 and the center of curvature of the notch 5Ilie on a common axis, the

attached. Consequently, this movement;y of the barrel casting causes thediamond nib to move in a path parallel to the table of the grindingmachine and therefore to dress a straight surface which is normal to thesides of the grinding wheel. l

As the diamond nib 4 proceeds along the outer periphery of the grindingwheel it will come to a point directly below the center of the iefthandcurve c of the wheel.- At this instant the left-hand contact members 81(Figures 4 and 1l) are caused to contact the right-handends ofthe screws88, the latter being adjusted to provide a contact at this particularpoint. Under these conditions further movement to the left of the barrelcasting 20 is precluded, so that the only movement possible for thepinion to make at this time in response to' further movement to the leftof the rack 29 is that of rotation. moment contact is establishedbetween the member 81 andv the screws 88, the center line of .the shaftI8 will coincide with the center of the curve c and will also be inlinewith the center point of the left-hand curved notches 8I. Consequently,the hub portions 42 of the shoe 4I will be in a position to rotatewithin the left-hand circular notches 8|, and the right-hand wingportion 43 of the shoe kwill be received by the deep slot formed betweenthe intermediate blocks 48 of the template. The shaft I9 will be causedto rotate in a clockwise direction, carrying with it the shoulder memberI8, the crank 3, the hub I6 and the diamond nib 4.

Since the center point of the left-hand circular notches corresponds inposition to the center point of the rounded edge c of the grindingwheel, the diamond nib will be caused to describe a circular path of anyradius determined by the length of the crank. As the rack continues tomove to the left the diamond nib will finally reach a point on thesurface c of the grinding diamond nib 4 will be caused to trace a pathof the desired predetermined radius, therefore dressing the curvedsurface b of the wheel. When the shaft I9 has been rotated inY thismanner through the. necessary angle, the flat surface of the righthand-wing 43 (Figure 7) of the shoe 4I will strike the upper surface of theright-hand intermediate block 48 (Figure 8) of the template, and furtherrotation of the shaft I8 is precluded.

As the rack 29 continues to rnove to the left, due to the continuedadmission of pressure fluid to the right of the piston 51, the movementof the rack can be communicated to the pinion 28 only as a transversemovement of the pinion, its shaft I9 and the shoe 4I. These threeelements are therefore moved bodily to the left, carrying with them thebarrel casting 20 which is adapted to slide with respect to the mainblock 32 at the dove-tail slide 30. The positional relationship betweenthe essential elements of the mechanism during the transverse movementof the shaft I9 'is shown in Figure 10.l It will be noted that duringthis movement no change is made in the position of the knurled knob 88and hence the trip lever 83 remains in the position in which it wasinitially set when the operation first started. The transverse movementof the barrel casting 20 causes a similar movement of the shouldermember I8 to' which the crank 3, the hub portion I8 and the diamondnib 4are wheel at which the curved portion merges with the left-hand side ofthe wheel. In case the pitch radius of the pinion 2,8 is equal to theradius of the curves b, c ofthe wheel, the diainond nib will move at aconstant linear speed over the entire periphery of the wheel includingthe `curved surfaces.

It will be noted from a comparison of Figures 9, 10 and l1, that the dog84 has been swinging through an arc while the nib was tracing thecurvature a and then is moved in a horizontal path while the surface aof the grinding wheel was being dressed, the dog finally moving inwardlyand upwardlyI during movement of the diamond nib 4 over the surface c ofthe grinding wheel, so that when the, surface has been completelydressed the dog 84 is caused to contact the trip lever 83. This movementof the trip lever releases the latch 82 from the insiderv surface of thecollar 19, permitting the spring 88 to push the collar to the right andgiving the' rod '88 a similar movement.

Referring now to Figure 6, an inward movement of the rod 89 to the leftcauses the enlarged portion 1I to be interposed between the conduitopenings 13, 15, thus cutting off pressure iluid.

from the conduitA 15. `As the enlarged portion 10 is moved to the leftthe conduit 15 is placed in communication with the exhaust passageway Atthe ber to the left of the main now caused to moveto the hub members 42of the shoe 4I are seated within the left-hand circular notches l 'ofthe template, and this proceeds until the lower at surface of theleft-hand wing portion 43 of. the shoe contacts the upper surface of theleft-hand block 48 of the template, at which time the shaft I9 isprevented' from further rotational movement.

It will be noted that, during this rotational movement of the shaft I8the'dog 84 will have broken contact with the trip lever 83 so that inorder to maintain the lever in this reverse position, preventing anymovement at this time of the valve rod 69, a tension spring 81 (Figure11) may be provided. The movement of the shaft I9 and the correspondingmovement of the diamond nib 4 is exactly the reverse of that describedin connection with the forward Amovement, so that the shoe 4I is nowcaused to move in a horizontal plane along the top surface of thetemplate 46 until the hub portions 42 reach the right-hand pair ofcircular notches 5I. At this time the diamond nib is directly below thecenter point of the curved edge b of the grinding wheel. The right-handpair of stop screws 65 is so adjusted that at this moment the contactmembers 61 at the right side of the barrel casting are caused to abutthe adjustable stops. Inasmuch as the longitudinal movement of thebarrel casting and its contained shaft is prevented by the adjustablestop screws 65, further movementl to the right of the rack 29 will causethe pinion 26 to be rotated in counter-clockwise direction, causingthediamond nib 4 to describe a circular path around the curved surface,b of the grinding wheel. When the pinion 26 has rotatedlthrough aninety-degree angle so that the diamond nib has reached approximately ahorizontal position at 'a point where the curved surface b merges withthe right-hand side of the grinding wheel, further movement of thepiston 51 is automatically precluded. This automatic stopping functionmay be obtained in any suitable and well known manner, for example bymeans of excessive back pressure built up between the left-hand sideofthe piston and the adjacent cylinder end by which pressure uid isby-passed through a relief valve (not shown) and thus prevented fromentering either the pilot valve or the hydraulic cylinder. a

From the foregoing it is evident that I have disclosed an improveddresser attachment for a grinding wheel, in which the dresser tool iscaused automatically to move from one side of the wheel around a curvedsurface of predetermined radius, then along a straight surface andfinally around another curved surface to the other'side of the wheel,after which the dresser tool iscaused to reverse its movement definingexactly the same path as it had during its forward motion. The wheel istherefore dressed twice, after which further movement of the diamond nibis automatically stopped in any suitable manner. It will be understoodthat if desired any number of excursions may be provided for the diamondnib byv simply'pulling the knob 86 to the left to reset the trip lever83 after the diamond nib has terminated its single excursion. Itisfurther apparent that all of the relative movements, both rotary y theright, producing ilrst p A a counter-clockwise rotation of the shaft I8since and slidable. are substantially frictionless in that the rollerbearings 22 permit the shaft -I9 to rotate relative to thebarrel casting20, and the ball bearings 38 permit the barrel casting 20 and the shaft|8410 move as a unit with respect to the metal block 32.

In order to prevent grinding dust-,from enterk ing any of these bearingsit may be desirable to provide the sheet metal box 5 over the main partof the attachment, and a smaller box 6 over that part of the attachmentwhich contains the pilot.

valve, permitting only the crank 3, the trip lever 83 and the startingknob 86 to be exposed, The attachment is preferably secured rigidly tothe table AI of the grinding machine, but may be normally positioned outof the way of the articles Ibeing momentarily ground so that when itbefor sequentially rotating said member and for comes necessary to dressthe wheel the table may be run a sulcient distance toward the grinding iwlieel to permit the diamond nib 4 accurately to dress the entirecutting periphery of the wheel.

It will be understood that I desire to comprehend within my inventionsuch modifications as come within the scope of the claims and theinvention. 1 Y

Having thus fully described my invention, what I claim as new and desireto secure by-Letters Patent, is:

1. A grinding machine attachment for dressing a grinding wheel having astraight peripheral portion and two'rounded edge portions, means formoving a dressing tool from one side of the wheel over one of therounded edges, then along the straight portion, then around the otherrounded edge, said means including a cylindrical member which carriesthe dressing tool, means `moving the member in a translatory directionparallel to the axis of the cylinder to correspond with the directionsof the rounded edge and straight peripheral portions of the grindingwheel surface, said last-mentioned means including a shoe secured tosaid member and a template over which the shoe rides to control therotational and translatory movements of said member whereby the dressingtool is caused to dress the entire cutting surface of the wheelincluding the rounded edges and means for reversing the move- `ment ofthe tool to cause the latter to retrace its path back to its initialposition whereby the entire abradingl surface of the wheel is dressedtwice.

2. A grinding machine attachment for dressing a grinding wheel having astraight peripheral portion" and two rounded edge portions, means formoving a dressing tool from one side of the wheel over one of therounded edges, then along the straight portion, then around the otherrounded edge, said means comprising a crank to which the dressing toolis secured and a crank shaft, said crank shaft being adapted to rotatewhen one of the rounded edge portions is` being dressed, then beingadapted to be moved in a direction parallel to the straight peripheralportion of the wheel in order to cause said portion to be dressed by thedressing tool, said shaft being then ladmited to be again rotated inorder to cause the dressing tool to move around the rethe axis of thecylinder to correspond withth directions of the rounded edge andstraight peripheral portions of the grinding wheel surface;

' rounded edges.

said last-mentioned means including a shoe secured to said member andatemplate over which the shoe rides to control the rotational andtranslatory movements of said member whereby the dressing tool is causedto dress the entire cutting surface of the wheel including the roundededges and means for reversing the movement of the tool to cause thelatter to retrace its path back to its initial position whereby theentire abrading surface of the wheel is dressed twice.

3. A grinding machine attachment for dressing Aa grinding wheel having astraight peripheral portion and two rounded edge portions, means formoving a dressing tool from one side of the wheel over one of therounded edges, then along the straight portion, then around the otherrounded edge, said means comprising a crank to which the dressing toolis secured, a crank shaft and a motor for operating said shaft, saidcrank shaft \being carried on a cylindrical member, means forsequentially rotating said member and for moving the member in atranslatory direction parallel to the axis of the cylinder to correspondwith the directions of the rounded edge and straight peripheral'portions of the grinding wheel surface, said last-mentioned meansincluding a shoe secured to said member and a template over which theshoe rides to control the rotational and translatory movements of saidmember whereby the dressing tool is caused to dress the entire cuttingsurface of the wheel including the rounded edges and means for reversingthe movement of said tool to cause the latter to retrace its path shaft,a pressure fluid motor for actuating said shaft, said motor beingadapted throughsuitable mechanism to rotate the shaft at the time one ofthe rounded edges of the grinding wheel is being dressed, then to movethe shaft in a direction parallel to the straight peripheral portion ofthe wheel during the time that the last-mentioned portion is beingdressed, and then to rotate the shaft in the same direction as before inorder to cause the dressing tool to dress the other rounded edge of thegrinding wheel, said-crankshaft being carried on a cylindrical member,means for sequentially rotating said member and for moving the member ina translatory direction parallel to the axis of the cylinder tocorrespond with the directions of the rounded edge and straightperipheral portions of the grinding wheel surface, said last-mentionedmeans including a shoe secured tosaid member and a template overWhich'the shoe rides to control the rotational and translatory movementsof said member whereby the dressing tool is caused to dress the entirecutting surface of the wheel including the A grinding machine attachmentfor dressing a/ grinding wheel having a straight peripheral portion andtwo rounded edge portions, means for moving a dressing tool from oneside of the the straight portion, then around the other rounded edge,said means lcomprising a crank to which the dressing tool is attachedand a crank shaft, a pressure fluid motor for actuating said shaft, saidmotor being adapted through suitable mechanism to rotate the shaft atthe time one of the rounded edges of the grinding wheel is beingdressed, then to move the shaft in a direction parallel to the'straightperipheral portion of the wheel during the time that the lastmentionedportion is being dressed, and then to rotate the shaft in the samedirection as before in order to cause the dressing tool to dress theother rounded edge of the grinding wheel, said pressure fluid motorcomprising a hydraulic cylinder with a double-acting piston, and meansincluding a pilot valve for controlling the admission of pressure uidalternately to the opposite sides of said piston whereby the motor movesthe shaft in a direction such as to cause the dressing tool to dress`the entire periphery of the grinding wheel including' both rounded edgeportions, and then the shaft is moved in the opposite direction to causethe dressing tool to retrace its movement over the grinding wheel, saidcrankshaft being carried on a cylindrical member, means for sequentiallyrotating said member and for moving the member in a translatorydirection parallel to the axis of the cylinder to correspond with thedirections of the rounded edge and straight peripheral portions of ,thegrinding wheel surface, said last-mentioned means including a shoesecured to said member and a template over which the shoe rides tocontrol the rotational and translatory movements of said member wherebythe dressing tool is caused to dress the entire cutting surface of thewheel including the rounded edges. 6. A dressing attachment for agrinding wheel which has rounded edges separated by a straight portion,said attachment comprising a dressing tool secured to the end of acrank, said crank being carried on a shaft, means for rotating the shaftto cause the tool to dress one of the rounded edges of thev wheel,`means for moving the shaft, crank and dressing tool within a plane whichpasses through the axis of the shaft and parallel to the straightportion of the grinding wheel whereby the dressing tool is caused tomove over the straight portion of the wheel periphery, and means forrotating the shaft upon conclusion of the planar movement of the shaftwhereby the dressing tool is caused to move over the other rounded edgeof the wheel, said means for moving the shaft, crank and dressing toolcomprising a cylindrical member, means for sequentially rotating saidmember and for moving the member in a translatory direction parallel tothe axis of the shaft to correspond with the directions of the roundededge and straight peripheral portions of the grinding wheel surface,said last-men- 1 tioned means including a shoe secured to said memberanda template over which the shoe rides to control the rotational andtranslatory movements of said member whereby the dressing tool is causedto dress the entire cutting surface of the wheel including the roundededges.

7. A dressing attachment for a grinding wheel .which has rounded edgesseparated by a straight portion, said attachment comprising a dressingtool secured to the end of a crank, said crank being carried on a shaft,means for rotating the shaft to cause the tool to dress one of therounded edges of the wheel, means for moving the shaft, crank anddressing tool'within a plane which wheel over one of the rounded edges,then along passes through the axis of the shaft and parallel portion,and finally over for rotating the shaft upon conclusion of the' theshaft whereby the dressplanar movement of move over the other roundeding tool is caused to edge of the wheel, shaft, crank and dressing toolcomprisingv a cylindrical member, means for sequentially rotating saidmember and for moving the member in a translatory direction parallel tothe axis of the shaft to correspond with the directions of the roundededge and straight peripheral portions of the grinding wheel surface,said last-mentioned means including a shoe secured to said member and atemplate over which the s oe rides to control the rotational andtranslatory movements of said member whereby the dressing tool is causedto dress the entire cutting surface of the wheel including the roundededges and means for causing the tool to retrace its path over onerounded edge, then over the straight peripheral the other rounded edgeto its initial position.

8. A grinding machine attachment for dressing a grinding wheel having astraight peripheral portion and two rounded end portions, a dressingtool carried by a crank, a crank shaft having a pinion, means forrotating said pinion in one direction to cause said tool to dress one ofthe rounded end portions of the wheel, and means for causing the pinionto move in a plane which passes through the shaft whereby the dressingtool dresses the straight peripheral portion of thev wheel, saidpinion-rotating means being thereupon again effective .to cause saidtool to dress the other rounded end portion, the pitch diameter of saidpinion being substantially equal to the radius of the two rounded endwheel portions whereby said dressing tool has the same linear speedthroughout its entire dressing operation. i

9. A grinding machine atta-chment for causing a dressing tool to bemoved over a grinding wheel surface having an outer peripheral portionwhich terminates at each end in a rounded edge, said attachmentcomprising a dressing tool secured to a crank, a crank shaft, a pinionon said shaft meshing with a rack, means for moving the rack.

While permitting the shaft to rotate whereby said tool dresses one ofthe rounded edges of the wheel, means for restraining the shaft fromrotation during further movement of the rack whereby the shaft, crankand dressing tool are moved in `a direction parallel to the straightperipheral portion of the wheel in order to dress said portion, andmeans for thereafter permitting rotation of the shaft during stillfurther movement of the rack whereby the other rounded edge of the wheelis dressed by said tool.

10. A grinding machine attachment for causing a dressing tool to bemoved over a grinding wheel surface having an outer peripheral portionwhich terminates at each end in a rounded edge, said attachmentcomprising a dressing tool'secured to a crank, a crank shaft, a pinionon said shaft meshing with a rack, means for moving the rack Whilepermitting the shaft to rotate whereby said tool dresses one of therounded edges of the wheel, means for restraining the shaft fromrotation during further movement of the rack whereby the shaft, crankand dressing tool are moved in a direction parallel to the straightperipheral portion of the wheel in order to dress said portion, andmeans for thereafter said means for moving the permitting rotation ofthe` shaft during still further movement of the rack whereby the otherrounded edge of the wheel is dressedby said tool, said rack-moving meanscomprising a hydraulic motor'controlled by a pilot valve.

11. A grinding machine attachment for causing a dressing tool to bemoved over a grinding i wheel surface having an outer peripheral portionwhich terminates at each end in a rounded edge, said attachmentcomprising a dressing tool secured to a crank, a crank shaft, 'a pinionon said shaft meshing with a rack, means for moving the rack whilepermitting the shaft to 'rotate whereby said tool dresses one of therounded edges of the wheel, means for restraining the shaft fromrotation during further movement of the rack whereby the shaft, crankand dressing tool are moved in a direction parallel to the straight'peripheral portion of the wheel in order to dress said portion, andmeans for thereafter permitting rotation of ,the shaft during stillfurther movement of the rack whereby the other rounded edge of the wheelis dressed by said tool, said rackmoving means comprising'adouble-acting hydraulic cylinder to which pressure uid is admittedalternately to opposite ends of the cylinder and controlled by a pilotvalve, a dog projecting outwardly from said shaft and in line with areversing lever on said pilot valve, said dog being so positioned thatafter the shaft has terminated its last rotational movement the dog willstrike the reversing lever of the pilot valve to cause pre/ssure iiuidto be admitted to the opposite end of the hydraulic cylinder whereby therack is caused to move in the opposite direction and the dressing toolis caused to retrace its path of movement to its initial position andthe grinding wheel periphery is dressed twice.

12. A grinding machine attachment for causing a dressing tool to bemoved over a grinding wheel surface which terminates in rounded edges,said attachment comprising a dressing tool secured to a crank, a crankshaft therefor, a pinion on the shaft meshing with the rack, means forrotating the pinion with respect to the rack so as to cause the dressingtool to move over one of the rounded edges of the grinding wheel, meansfor moving the rackand pinion as a unit in the direction of the lengthof the rack to cause the dressing tool to be moved over the periphery ofYthe grinding wheel, and means for rotating the pinion with respect tothe rack in order to cause the dressing tool to move over the otherrounded edgeof the grinding wheel. v

13. A grinding machine attachment for causing a dressingtool to be movedover a grinding wheel surface which terminates at each end in a roundededge, means for moving said tool first over one of the rounded edges ofthe wheel, then over the peripheral portion of the wheel and finallyover the other rounded edge of the wheel, said means including a-shaftand a crank mounted thereon carrying the dressing tool, a pinion securedto said shaft and adapted to be actuated by a rack, means for moving therackwhile permitting rotation of the shaft whereby the dressing tool iscaused to dress one of the rounded edges of the wheel, and means forpreventing further rotation of the shaft when the rack .is actuatedwhereby the shaft, crank and dressing tool are moved as a unit in ahorizontal direction across the periphery of the wheel, saidrotationpreventing means being rendered inoperative at the terminationof said horizontal movement whereby the shaft and crank are permitted torotate as the rack is actuated further and the dressing tool is carriedaround the other rounded edge of the/wheel.

14. A grinding machine attachment'for causing a dressi'rg tool to bemoved overa grinding wheel surface which terminates at each end in arounded edge, means for moving said tool first over one of the roundededges ofthe wheel, then over the peripheral portion of the wheel andsaid means including a shaft and a. crank mounted thereon carrying thedressing tool, a pinion secured to said shaft and adapted to be actuatedby a'rack, means for moving the rack while permitting rotation of theshaft whereby the dressing tool is caused to dress one of the roundededges of the wheel, and means for preventing further rotation of theshaft when the rack is actuated whereby the shaft, crank and dressingtool are moved as a unit in a horizontal direction across the peripheryof the wheel, said rotation-preventing means being rendered inoperativeat the termination of said horizontal movement whereby the shaft andcrank are permitted to rotate as the rack is actuated further and thedressing tool is carried around the other rounded edge of the wheel,said rotation-preventing means comprising a shoe secured to said shaftand having fiat and rounded surfaces, the fiat surface of said shoebeing adapted to slide over the fiat surface of a template, thelast-mentioned surface being provided with a pair of spaced circularnotches having a circularity which corresponds to the round surface ofsaid shoe, said round surface of the shoe being adapted to rotate in thefirst circular notch in the template during the first rotational effortof the shaft, after which the flat surface of the shoe slides over theflat surface of the template and then the round surface of the shoerotates in the other circular notch of the template at the terminationof `the movement over the fiat surface of the template in order topermit the shaft again to rotate and to cause the dressing tool to dressthe remaining rounded edge of the Wheel.

15. A grinding-machine attachment for causing. a. dressing tool to bemoved over a grinding wheel surface which has a rounded edge at eachend, means for moving said tool first over one one of the rounded edges,then over the outer periphery of the wheel and then overthe otherrounded edge of the wheel, saic'. means including a shaft carrying acrank at one end and a shoev vcylindrical portion of the shoe to fititself within one of the circular notches whereby the shaft is adaptedto rotate and the dressing tool is caused to move over one of therounded edges of the wheel, said last-mentioned means serving to movethe flat surface of the shoe along the flat surface of the template atthe conclusion of the rotating movement to 1cause the shoe, shaft, crankand dressing tool to move in a horizontal plane until the shoe reachesthe second circular notch, whereupon the cylindrical portion of the shoeis caused to rotate within said notch and the shaft, crank and dressingtool are rotated to rounded edge of the grinding wheel whereby theentire grinding surface of the wheel is dressed.v

16. A grinding machine/attachment for causing a dressing tool to bemoved over a grinding 5 wheel surface which has a rounded edge at eachend, means for moving said tool first over one of the rounded edges,then over the outer periphery of the wheeland then over the otherrounded edge of the wheel, said means including a shaft carrying a crankat` one end and a shoe atthe finally over the other rounded edge of thewheel, N

other end, said-dressing tool being secured to said crank, a pinionsecured to the shaft inter; ,mediate the crank and shoe. a rack foractuating said pinion, said shoe having a circular portion provided witha flat surface and resting on a template having a fiat horizontalsurface which terminates at each end in a circular notch, means formoving said rack in a. horizontal direction while the cylindricalportion of the shoe is in one of the circular notches of the templatewhereby the shaft, crank and ressing tool are rotated and said tool iscause to dress one of the rounded edges of the wheel, the fiat surfaceof said shoe being adapted to move along the flat surface of thetemplate on further movement of said rack whereby the shoe, shaft, crankand dressing tool are caused to move in a horizontal plane in order todress the outer peripheral portion of the wheel, said shoe continuingthis planar movement until it reaches the second circular notch in thetemplate whereby upon further movement of the rack the shaft, crank anddressing tool are coused to rotate in order to dress the other roundededges of the wheel, and

means for reversing the direction of travel of the rack` in order tocause the shaft, crank and dressing tool to rotate in the oppositedirection during the'time that the. cylindrical portion of said shoe isin the second circular notch of .the

40 template, further movement of said rack in the reverse direction andthe dressing tool is caused to redress the outer peripheral portion ofythe wheel, further movement of the rack in the reverse direction movingthe shoe to such a position that its cylindrical portion coincides withthe other circular notch of the template whereby the shaft, crank anddressing tool are caused to rotate in the reverse direction and thedressing tool is returned toits initial position after having dressedboth rounded edges and the intervening peripheral portion of the wheeltwice.

1'?. 'A grinding machine attachment for causing a dressing tool-to bemoved over a grinding wheel surface which has a pair of rounded edges,means for moving said tool over one of the rounded edges, then over thelperipheral surface and then over the remaining rounded edge of thewheel, and means for reversing the movement of the tool so that the toolis caused again to dress both rounded edges of the wheel and theperiphery of the Wheel, said means including a cylindrical member whichcarries the dressing tool, means for sequentially rotating said memberand for moving the member in a translatory direction parallel to theaxis of the cylinderto correspond with the directions of the cause thedressing 11001 t0 move Over the 0the1"75 wheel surface which has a pairof rounded edges.

means for moving said tool over one of the rounded edges, then over theperiphery of the wheel and finally over the other rounded edge, saidmeans including a shaft carrying a crank at one end and a shoe at theother end, said dressing tool being mounted on saidvcrank, a pinionsecured to the shaft intermediate the crank and shoe, a rack foractuating said pinion,

and means including a template on which the shoe rests for permittingrotation of the shaft as the rack is moved during the time that thedressing tool is being movedv over one of the rounded edges, said. meansalso serving to prevent rotation of .the shaft as the rack is furthermoved whereby the movement of the rack is translated to the shaft as amovement in a plane which passes through the axis of the shaft so as tocarry the dressing tool'over the outside periphery of the wheel, saidmeans serving finally to permit rotation of'the shaft as the rack isfurther moved in order to cause the dressing tool to be moved over theother rounded edge of the wheel.

19. A grinding machine attachment for causing a dressing tool to bemoved over a grinding wheel surface which has a pair of rounded edges,means for moving said tool over one of the rounded edges, then over theperiphery of the wheel and finally over the other rounded edge, saidmeans including a shaft carrying a crank at one end and a shoe at theother end, said dressing tool being mounted on said crank, a pinionsecured to the shaft intermediate the crank and shoe, a rack foractuating said pinion, and means for permitting rotation of the shaft asthe rack is moved in order to carry the dressing tool around one of therounded edges of the wheel, said means also serving to prevent rotationof the shaft as the rack is further moved whereby the further movementof .the rack is translated to the shaft as a movement in a plane whichpasses through the axis of the shaft so as to carry the dressing toolover the outside periphery of the wheel, said means also serving topermit rotation of the shaft on further movement of the rack in order tocarry the dressing tool over the other rounded edge of the wheel, saidmeans including a template having a pair of spaced circular notches andan intervening fiat surface, said shoe being adapted to rotate first inone notch in order to permit the shaft to rotate, then over the flatsurface of the template to prevent rotation of the shaft, and

finally to rotate in the second notch to permit the shaft to rotate andto carry the dressing tool through the corresponding movements in orderto dress the entire periphery of the wheel including both rounded edges.

20. A grinding machine attachment for causing a dressing tool to bemoved over a grinding wheel surface which has a pair of rou'nded edges,means for moving said tool over one of the rounded edges, thenv over theperiphery of the Wheel and finally over the other rounded edge, saidmeans of the rack is translated to the shaft as a movement in a planewhich passes through the axis of the shaft so as to carry the dressingtool over the outside periphery of the wheel, said means also serving topermit rotation of the shaft on further movement of the rack in order tocarry the dressing tool over the other rounded edge of the Wheel, saidmeans including a template havinga pair of spaced circular notches andan intervening at surface, said shoe being adapted to rotate first inone notch in order .to permit the shaft to rotate, then over the flatsurface of the template to prevent rotation of the shaft, and nally torotate in the second notch to permit the shaft to rotate and to carrythe dressing tool through the corresponding movements in order to dressthe entire periphery of the wheel including -both rounded edges, andmeans for reversing the movement of the rack when the dressing tool hasreached .the end of the last rounded edge of the wheel whereby theshaft, crank and dressing tool are caused to retrace their pathsincluding the path over the template and the dressing .tool is movedfirst over one rounded edge of the wheel, then over the outsideperiphery of the wheel and nally over the other rounded edge of thewheel to its initial position.

21. A grinding machine attachment for causing a dressing tool to bemoved over a grinding wheel surface which ,has a pair of rounded edges,meansv for moving said tool over one of the rounded edges, then over theperiphery of the Wheel and finally over the other rounded edge, saidmeans including a shaft carrying a crank at one end and a shoe at theother end, said dressing tool being mounted on said crank, a pinionsecured to the shaft intermediate the crank and shoe, a rack foractuating said pinion, and means for permitting rotation of the shaft asthe rack is moved in order to carry the dressing tool around one of therounded edges of the wheel, said means also serving to prevent rotationof the shaft as the rack is further moved whereby the further movementof the rack is translated to the shaft asa i movement in a plane whichpasses through the axis of the shaft so as to carry the dressing toolover the outside periphery of the Wheel, said means also serving topermit rotation of the shaft on further movement of the rack in order tocarry the dressing tool over the other rounded edge of the wheel, saidmeans including a template having a pair of spaced circular notches andan intervening at surface, said shoe being adapted to rotate nrst in onenotch in order to permit the shaft to rotate, thenover the at surface ofthe template to prevent rotation of the shaft, and finally to rotate inthe second notch to permit the shaft to rotate and to carry the dressingtool through the corresponding movements in order to dress .the entireperiphery of the wheel including both rounded edges, said rack-actuatingmeans comprising a double-acting uid cylinder for moving the rack rst inonedirection and then in the other direction, the direction of pressureuid admitted to said cylinder being controlled by a pilot valve which inturn is controlled by a dog secured to the shaft and operating inresponse to a predetermined rotation of the shaft to reverse theoperation of said pilot valve and thereby reverse the movement oftherack.

JOHN C, WILSON.

